1. Field of the Invention
The present invention relates to connectors configured to connect to multiconductor ribbon cable and, in particular, concerns a connector that is configured to connect to both signal conductors and ground conductors defining a ground bus in the multi-conductor cable.
2. Description of the Related Art
Ribbon cable is a type of cable which has a plurality of conductors positioned adjacent each other in a single plane. Typically, the conductors are encased in a flexible insulating material, such as vinyl, which follows the contours of the parallel closely spaced conductors in the ribbon cable. Ribbon cable is often used to interconnect computer components. One common example of the use of ribbon cable is to connect motherboards in personal computers to disk drives. Further, ribbon cable is also often used to interconnect computers to accessory equipment.
Generally, connectors are used to interconnect the cables to various devices. These connectors have a plurality of contacts which are configured to contact the conductors within the ribbon cable and also to provide a pin connection to a matching connector or pin array. Typically, the connectors include a plurality of contacts that have an insulation displacement end that pierces the insulation surrounding the conductor in the ribbon cable and contacts the embedded conductor, and a mating end that provides a connection point for pins of a mating connector or pin array.
The typical connector is generally rectangular in shape and has an opening which receives the ribbon cable so that the connector spans the width of the ribbon cable. The insulation displacement ends of the plurality of contacts are positioned within the connector so that when the connector is closed around the ribbon cable, the insulation displacement ends pierce the insulation surrounding the conductors of the ribbon cable and form an electrical connection with each of the conductors within the ribbon cable. It will be appreciated that the contacts are exactly positioned within the connector so as to be able to contact and make an electrical connection with the corresponding conductor within the ribbon cable.
One typical ribbon cable assembly application used in the prior art has forty conductors that are spaced on 0.050xe2x80x3 centers. Of the forty conductors within the cable, seven of these conductors are dedicated as ground conductors and the remaining thirty-three are data line or signal conductors. This type of ribbon cable complies with ANSIx3.279-1996 specification. The structure of the prior art ribbon cables results in these ribbon cables having an upward limit of approximately 16 MB/Sec. data transfer rate over the ribbon cable.
As computers have become increasingly more powerful, there has been a desire to increase the rate of data transmnission over ribbon cables. This has resulted in the creation of a new ribbon cable specification, the SFF-8049 specification. Ribbon cables corresponding to the SFF-8049 specification will now have eighty conductors that are spaced apart on 0.025xe2x80x3 centers. Hence, the ribbon cable under the new specification will have the same general size, otherwise known as form factor, as the ribbon cable of the prior art. The ribbon cable of the new specification retains the forty original signal conductors, the 33 data conductors and the 7 ground conductors, of the prior art ribbon cable. This permits use of the new specification cable in the place of the old specification ribbon cable without requiring the alteration of the input and output devices that are connected to the ribbon cable.
However, the forty additional conductors that are added to the ribbon cable of the new specification are all ground conductors that are positioned between each of the original forty conductors. Consequently, the original signal conductors are separated from each other by a dedicated ground conductor in the new specification cable. Hence, the forty additional ground conductors form a ground bus which results in the new specification ribbon cable being able to transmit data at a significantly higher rate than the old specification ribbon cable.
However, the introduction of the new specification ribbon cable has complicated the task of connecting devices to the new specification ribbon cable. In particular, the forty conductors forming the ground bus must be grounded to each termination of the ribbon cable and at any mid-length connection to the ribbon cable for the ground bus to function most effectively. Presently, to achieve this connection, a first prior art connector that was originally configured to attach to the forty original conductors is slightly modified so that the contacts will selectively engage with the forty original signal conductors in the new specification cable when mounted on the ribbon cable. A second connector, similar in construction to the first connector, that is configured to attach to the forty alternating ground conductors that comprise the ground bus is then mounted on the ribbon cable.
While the use of the two connectors results in adequate connection to the forty original signal conductors and the forty added ground conductors, using two connectors is more costly and also increases the possibility of poor connection to the conductors within the ribbon cable. Further, the use of two connectors at each termination or mid-length connection to the ribbon cable complicates the use of the ribbon cable particularly in environments where the space surrounding the ribbon cable is limited.
Moreover, it is desirable to attach the seven original grounded signal conductors to the ground bus at each connector. Presently, this is accomplished by stringing jumpers between the pin connections of the seven ground conductors on the first connector to the ground contacts on the second connector. However, this sort of interconnection complicates the installation of the connectors to the new specification ribbon cable as this must typically be done by hand after the cable has been installed. Hence, there is a need for a connector that can be connected to the new specification ribbon cable which will connect to both the forty original signal conductors and also to the forty ground bus conductors. This connector should preferably have a form factor that is substantially the same as the form factor of the connectors used in the prior art. Further, this connector should also be configured so that interconnection between the forty ground conductors and the seven original signal ground conductors is simplified.
The aforementioned needs are satisfied by the connector of the present invention which comprises a first member having a receiving surface that is configured to receive a ribbon cable and a base member that engages with the first member so as to position a first surface of the base member adjacent the receiving surface of the first member. The base member has a plurality of receptacles or openings that are configured to receive contacts wherein the plurality of receptacles are positioned within the base member. Specifically, the connector is configured so that a first plurality of contacts can be positioned within the receptacles so as to make electrical contact with a first group of conductors within the ribbon cable and a second plurality of receptacles that are configured to receive a second plurality of contacts so that the second plurality of contacts can make electrical contact with a second group of conductors within the ribbon cable.
The first plurality of contacts are configured to make electrical contact with the first group of electrical conductors within the ribbon cable that, collectively, comprise a ground bus. Preferably, the first plurality of ground contacts are electrically interconnected so as to maintain the integrity of the ground bus. Further, the second plurality of contacts are configured to make electrical contact with the second group of electrical conductors within the ribbon cable that are signal conductors within the ribbon cable. Preferably, the second plurality of contacts include pin connections that permit external connection to the signal conductors within the ribbon cable via the connector.
In one embodiment, the connector incorporates signal contacts which have an insulation displacement end and a mating end. The insulation displacement end is configured to displace the insulation of the ribbon cable and make contact with the wire embedded therein. The mating end is configured to make a resilient pin contact for connection to a mating connector or pin array. The contacts are positioned within the body of the connector so that the mating end of the contacts are positioned within openings in the body so as to allow access to the mating connector or pin array. The insulation displacement end is preferably comprised of two blades with a gap therebetween. The two blades are preferably sized and configured to displace the insulation surrounding an embedded conductor within the ribbon cable so that the embedded conductor will be positioned between the two blades and thereby make electrical contact.
In one aspect of the present invention, the connector is configured to be used in conjunction with ribbon cable which incorporates a plurality of signal conductors and a plurality of ground conductors. The ground conductors forming a ground bus are preferably positioned between each of the signal conductors in the ribbon cable. The connector is arranged so that there are a plurality of rows of contacts wherein a first row is positioned within the connector so that when the ribbon cable is positioned within the cable receiving area of the connectors, the first row of contacts is connected to alternating conductors of the ribbon cable which comprise the ground conductors. The second row of contacts are positioned within the connectors so that the second row of contacts are connected to signal conductors within the ribbon cable. A third row of contacts may also be added to make contact to additional signal conductors.
In one embodiment, the connector is configured to be used with SFF-8049 ribbon cable which has forty signal conductors and forty ground conductors positioned within the cable. The connector of the preferred embodiment has three or more rows of contacts that are arranged in the first direction across the width of the cable receiving area. The center row of contacts is positioned so as to be connected to each of the forty conductors comprising the ground bus. In particular, the contacts are positioned within the connector so that when the connector is attached to the ribbon cable, the contacts make electrical contact with alternating conductors within the ribbon cable that form the ground bus. The two outer rows of contacts of the connector of the preferred embodiment are each configured to connect to twenty of the remaining forty signal wires within the ribbon cable.
In another aspect of the present invention, the connector is configured to include a first plurality of contacts that connect to signal conductors within the ribbon cable and a second plurality of contacts that connect to ground conductors within the ribbon cable, and the connector is configured so that contacts connected to the ground bus, that are adjacent to signal conductors that are grounded signal conductors, can be interconnected in the connector. In the preferred embodiment, the contacts that are connected to the ground conductors include tabs that can be bent so as to make an electrical connection with contacts that are connected to grounded signal conductors.
From the foregoing, it will be appreciated that the connector of the preferred embodiment includes contacts that are mounted within a base that preferably has a form factor similar to prior art connectors, and the connector is configured to be able to be attached to both signal conductors and ground conductors within a ribbon cable. The use of a single connector simplifies the process of connecting ribbon cable to additional devices. Further, the interconnection between the ground bus and grounded signal conductors within the ribbon cable is simplified by the use of ground bus contacts within the connector that can be readily connected to adjacent signal conductor contacts. These and other objects and advantages of the present invention will become more fully apparent from the following description taken in conjunction with the accompanying drawings.